Process for purifying pitch-oil and other ethereal oils obtained by destructive distillation of resinous substances.



UNITED STATE FATENT OFFICE.

ALBERT HESSE, OF WILMERSDORF; GERMANY.

PROCESS FOR PURlFYlNG PITCH-OIL AND OTHER ETHEREAL OILS OBTAINED BY DESTRUCTIVE DISTILLATION F RESINOUS SUBSTANCES. I

Patented Nov. 13, 1906. i

Application-filed April 12, 1906. Serial Nn. 311,207.

stances, of which the following is a full, clear,

and exact specification.

Among the turpentine-oils of commerce the American and French turpentine-oils are more valuable than turpentine-oils coming from other countries, and which are more correctly named pitch-oils. These oils are obtained by the destructive distillation of resinous substances of different kinds, such as wood from resinoustrees and the like, colophonium, -&c. They are generally termed pitch-oils, pine-oils, wood-turpentine, stump-turpentine, wood-spirits, resinous oils, and like names-in German, kienole, harzole. These oils are referred to in the well-known standard work Die dther'ischen Oele, by E. Gildemeister and Fr. H'ofimann, Berlin, 1899, pages 329-333, in the chapter entitled Kienle, see also Ino M. McCandless, Journal of the American Chemical Society, 26, pages 981985. This difierenceis partly caused by the different methods used when preparing these oils, for these pitch-oils are obtained by destructive distillation of resinous substances, while the genuine turpentine-oils are prepared by distilling pine-resin with steam. Moreover, the parts of the plants or the exuded matter. used or preparin pitch-oils often contain substances whic cause ill-smelling com ounds to be formed. The nature of these il -smelling compounds has not been ascertained up to date; but their intensely bad smell, notwithstanding their small quantity, renders it impossible to use the said oils for many. purposes. Many attempts have been made for eliminating these malodorous com ounds in order to render these oils as valua le as the genuine turpentine-oils. These methods are used partly on a saponifying and partly on an oxidizing treatment of the oils; but the smell of the commercial pitch-oils purified by these methods shows that this treatment is not suflicient for eliminating the ill-smelling substances, and this has been confirmed by many experiments. Now I have found that by treating these oils with alkali 'metals or alkaline-earth metals (both hereinafter comprised under the expression alkaline metals") the compounds causing the disagreeable smell are transformed into nonvolatile compounds. Consequently it is possible out diii'iculty a product from which the inalodorous compounds are eliminated by distilling the oil with addition of small quantities of an alkali metal or an alkaline-earth metal. A remarkably small quantity of alkali metal or alkaline-earth metal is sullicient for eliminating. the ill-smelling substances, and the process can therefore be carried out on an industrial scale with good success and cheaply to obtain in a very simple manner and with-' notwithstanding the relatively high pllce of the reagents used. The distillation Wit'i addition of alkaline metals may be receded by a purification with alkaline or alkalineearth hydroxide, this purification being executed in the known manner.

When compared with other processes, and especially with those in which the ill-smelling compounds are to be eliminated by an oxidizing treatment, my new process has the advantage that a loss of valuable substances is avoiiied, as no destruction of-the unsatu rated compounds, which form the'most valuable part of the oils, takes place, while in the oxidizing processes such destruction may occur.

In practically carrying out my process I proceed, for instance, as follows:

Example 1 Into one thousand kilos of Russian tu entine-oil (more correctly pitchoil) three ki es of metallic sodium are stirred. The oil is then distilled under ordinary pressure. If necessary, the distillate, or a part thereof, is again treated in the same manner.

Example 2: One thousand kilos of American wood-oil are boiled for an hour with five kilos of caustic soda and'thirty kilos of alcohol. The alcohol is then removed by distillation or by washing, and the sa onified oil is then distilled in vacuo after ing with two kilos of the liquid alloy of potassium and sodium.

Example 3: One thousand kilos of Polish itch-oil are heated with five kilos ofcalcium iiydroxid and then distilled in 'vacuo or under ordinary pressure with addition of 1.5 kilos of metallic calcium. If necessary, the distillate is again treated in the same manner.

What I claim is 1. The hereinbefore-described process of eliminating the ill-smelling substances from ethereal oils obtained by destructive distillation of resinous substances, said process consisting in distilling the oils with addition of 'I pitch-oils, said process consisting in distilling the oils with addition of alkaline metals,

substantially as described.

4. The hereinbefore-described process of.

eliminating the ill-smelling substances from pitch-oils, said process consisting in distilling the oils in vacuo with addition of alkaline metals, substantially as described.

In testimony that I claim the foregoing as my'invention I have signed my name in presence of two subscribing witnesses.

ALBERT HESSE.

Witnesses HENRY HASPER, WoLDEMaR HAUPT. 

